Crossbar switch

ABSTRACT

A crossbar switch is shown which utilizes a plurality of select units and a plurality of hold unit assemblies mounted on a frame. All of the armatures for the select units are located on one end of the crossbar switch frame, and a plurality of select-offnormal switches are positioned on the opposite end. Each hold unit is composed of a hold armature assembly, a plurality of fixed contacts, a plurality of movable contacts under the control of movable cards and a plurality of select fingers, which in conjunction with the hold armature, translate the selected cards to close the movable contacts which are under the control of the selected card. There is also provided a select finger holder having a plurality of mounting posts which frictionally engage the support member of the hold unit, said holder further including a plurality of mounting buttons for receiving and supporting the select fingers.

United States Patent Symes June 27, 1972 GTE Automatic ElectricLaboratories Incorporated, Northlake, Ill.

[22] Filed: Mayltl,197l

[21] Appl.No.: 141,876

[72] inventor:

[73] Assignee:

[52] 0.8. Ci. ..200/l75, 200/1 R, 335/1 12 [SI] ..H0lh 9/00 [58] Fieldof Search ..200/l R, 166 J, 175, I76, 177; 335/112 {56] References CitedUNITED STATES PATENTS 2,643,299 6/1953 Bellamy ..200/177 3,445,7955/1969 Holtfreter et al. ..335/112 3,478,285 11/1969 Haines et a1..335/1 12 3,509,301 4/1970 De Smet ..200/l75 X Primary Examiner-U. R.Scott Attorney-K. Mullerheim, B. E. Franz and David W. Heid [57]ABSTRACT A crossbar switch is shown which utilizes a plurality of selectunits and a plurality of hold unit assemblies mounted on a frame. All ofthe armatures for the select units are located on one end of thecrossbar switch frame, and a plurality of selectoff-normal switches arepositioned on the opposite end. Each hold unit is composed of a holdarmature assembly, a plurality of fixed contacts, a plurality of movablecontacts under the control of movable cards and a plurality of selectfingers, which in conjunction with the hold armature, translate theselected cards to close the movable contacts which are under the controlof the selected card There is also provided a select finger holderhaving a plurality of mounting posts which frictionally engage thesupport member of the hold unit, said holder further including aplurality of mounting buttons for receiving and supporting the selectfingers.

7 Claims, ll Drawing Figures PATENTEDJUHN I372 3.673 .366

sum 3 or 7 PMEN'I'ED JUN 27 1973 3 6 73 3 6 6 saw u or 7 PMENTEBJUH 2 7m2 3 6 73.366 SHEET 5 OF 7 FIG. 5

cnossmm SWITCH BACKGROUND OF THE INVENTION ample U.S. Pat. No. 3,366,90]to Keller, issued .Ian. 30, I968 and US. Pat. No. 3,445,795 toHoltfreter et al, issued May 20, I969. The Holtfreter et al crossbarswitch is typical of some of the crossbar switches which are presentlyin use, and in some respects is similar to the crossbar switch disclosedherein. In quite broad tenns, it can be said that the typical crossbarswitch is composed of a group of select magnet assemblies and a group ofbold magnet assemblies. Interaction between the select assemblies andthe hold assemblies closes the desired electrical contacts throughmechanical operation of the hold armatures. As might be surmised fromthe name, the select magnet assemblies precondition or select thedesired group of movable contacts to be connected to a corresponding setof stationary contacts, and the hold magnet assemblies close and retainclosed the selected contacts.

In the crossbar switch disclosed in the Holtfreter patent, each holdunit assembly includes a plurality of cards each having an aperture inone end through which a select finger is inserted. Each card controlsthe opening and closing of a number of movable electrical contacts whichextend through slots in the card, these movable contacts being matedwith stationary electrical contacts supported on the hold assembly. Eachselect bar includes a plurality of operators, with one operator for eachpair of select fingers on the associated switch level. When a select baris rotated, each operator on that bar moves the corresponding selectfinger into a restricted area within the card aperture associated withthe translated select finger. Thereafter, activation of the holdarmature on a hold unit assembly translates the selected cards andthereby closes the movable contacts associated with the selected card.As shown in Holtfreter, each hold unit assembly contains ten cards undera control of five operators which are positioned between five pairs ofselect fingers. In the Holtfreter patent the sets of select fingerswhich extend through the cards are mounted on individual mounting postswhich were individually affixed to the support plate of the hold unitassembly. Since there were five sets of select fingers, this requiredaffixing five individual mounting posts to each support plate of thehold unit assembly. Five select bars with one each select armature perbar are used and the five armatures for the five select bars are locatedon alternate ends of the crossbar frame. Consequently, there are threeselect armatures on one end of the frame and two on the opposite end,all requiring a relatively large amount of space on each end. Thisspacing of the select armatures on alternate ends of the crossbar frameincreased the overall length of the frame, thus increasing the width ofthe mounting racks which support the crossbar switches.

SUMMARY OF THE INVENTION According to one feature of this invention,there is provided a one-piece select finger holder having a mountingbutton for each select finger set and a plurality of mounting postsadapted to frictionally engage the support member of the hold unitassembly. The one-piece select finger holder may be molded in a singleunit and pressed into place on the support member, thus avoiding theproblem of individually mounting a number of buttons on each supportmember.

According to another feature of this invention, the mounting buttonsprovided on the unitary select finger holder are substantiallysemicircular. When a select finger set, which has a generally circularshaped bight therein, is inserted into the groove provided in eachbutton, a portion of the bight remains exposed beyond the button. Withthis arrangement a damaged select finger set may be easily removed froma button by grasping the exposed portion ofthe bight.

According to an additional feature of this invention, the grooveprovided in each button is "angled" such that it biases the selectfingers into the base portion of the card aperture.

According to another feature of this invention, all of the selectarmatures are positioned on the same end of the crossbar switch frameand the corresponding electromagnets for each select armature arepositioned on alternate sides of the associated frame end plate,resulting in a reduction of overall frame length.

According to still another feature of this invention, the crossbarswitch frame includes a member which is channeled to provide increasedstrength to the frame.

These and other features of the invention will be better understoodafter a perusal of the detailed description and the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a partial front view of thecrossbar switch assembled in accordance with this invention;

FIG. 2 is a top view of the crossbar switch shown in FIG. 1;

FIG. 3 is a view of the right end of the crossbar switch of FIG. I;

FIG. 4 is a view of the left end of the crossbar switch illustrated inFIG. 1;

FIG. 5 is a sectional view taken along section 55 of FIG.

FIG. 6 is an enlarged perspective view of a hold unit with theassociated select bars and operate fingers as incorporated in thecrossbar switch of FIG. I;

FIG. 7 is an enlarged perspective view of a select finger holder inaccordance with the invention, with a portion thereof broken away toshow one of the mounting posts incorporated therein;

FIG. 8 is an enlarged perspective view of the select finger holder inaccordance with the present invention;

FIG. 9 is a view of the right end of the select finger holder as shownin FIG. 8;

FIG. 10 is an enlarged perspective view of a select finger set used inthe hold units; and

FIG. II is a side view of the select finger set illustrated in FIG. 10.

DETAILED DESCRIPTION As shown in FIGS. 1-4, crossbar switch 13 iscomposed ofa number of hold unit assemblies 14 and a number of selectunits 15. The select and hold units are supported by a frame which iscomposed ofa lower plate 16 and an upper plate I7 which are welded toleft and right end plates 18 and I9 respectively. Mounting straps 20 and21, which include mounting holes 30, are welded to the upper and lowerframe plates 17 and I6 respectively, and provide facilities for mountingthe crossbar switch in a rack-type arrangement.

As can readily be seen in FIGS. I and 2, select bars 52 are supportedbetween end plates 18 and I9 by screws 22 and 23 which are threadedthrough end plates I8 and 19 respectively. A portion of the uppermostselect bar 52 and the corresponding select finger set 27 have beenomitted from FIG. 1 to more clearly show cards 39. Each select bar 52has rigidly attached thereto armatures 24 which are associated withelectromagnets 25, which when activated, pivot select bars 52 in thedirection of the electromagnet so energized. Each select bar 52 hasassociated therewith and rigidly attached thereto an operate finger 26for each hold unit assembly I4. Each operate finger 26 is insertedbetween a pair of select fingers 27. The operation of this arrangementwill be fully described subsequently. At this point it should be notedthat in the present crossbar switch 13, all of the select annatures 24and their corresponding select magnets 25 are located on the same end ofthe frame, with the select armature 24 and select electromagnets 25 forany one select bar 52 being located on alternate sides of end plate 18.In prior art arrangements such as in U.S. Pat. No. 3,445,795, some ofthe select armatures and their corresponding electromagnets for theselect bars were placed on one end of the frame and the remainder wereplaced on the opposite end of the frame. However, by placing all of theselect armatures 24 and their corresponding electromagnets 25 on thesame end of the frame, in the manner illustrated in the drawing, theoverall length of the crossbar switch is significantly reduced.

During operation of the crossbar switch, it is desirable to know which,if any, of the select bars 52 have been activated and also in whichdirection they have been activated.

An indication of which select bar 52 has been rotated and in whichdirection is provided on crossbar switch I3 by a group ofselect-off-normal switch assemblies designated 29, which are best shownthrough FIGS. 1 and 3. One selcct-offmormal assembly 29 is provided foreach select bar 52 and is activated by a select-olf-normal pindesignated 28. In FIG. 3 it can be seen that select bar 52 which is thesecond up from the base of the crossbar switch 13 has been operated suchthat the lower pair of contacts on the selectoff-normal switch 29 hasbeen closed, thus indicating that the upper electromagnet associatedwith that select bar 52 has been activated. The selectoff-normalassemblies 29 perform a second function in addition to indicating whichselect bar 52 has been activated. As can best be seen from FIGS. 2 and3, each select-off-normal switch assembly 29 has a pair of flat springs31 which extend outward from the assembly, with one spring located oneach side of the select-off-normal pins 28. The springs 3i retain theunoperated select bars 52 in a neutral position, as shown in FIG. 3.FIG. 5 illustrates the aforementioned neutral position of the fourunoperated select bars 52 and their associated operate fingers 26. Thelower spring of pair 31 which is associated with the select bar 52 whichhas been operated will return this operated select bar 52 to the neutralposition once the electromagnet 25 associated with the operated selectbar 52 has been de-energized.

In FIGS. 35 it can readily be seen that lower plate 16 in cludes anumber of channels which extend the length of the frame. By channelinglower plate 16, additional strength in torsion and deflection isachieved, resulting in a frame more sturdy than a conventional oneemploying non-channeled members of equal thickness. Thus it can beappreciated that by channeling the frame members, it is possible toachieve the required frame strength using plates of a lesser thicknessthan that required when only flat frame members are employed.

Now turning to FIG. 6, there is shown an enlarged perspective view of atypical hold unit 14, a portion of the select bars 52 and the operatefingers 26, as used in crossbar switch 13 of this invention. The holdunit 14 is composed of a support member 32, which forms the basicfoundation to which the remaining elements of the hold unit areattached. Hold magnet assembly 33 is composed of a motor unit 34, and anarmature 35 which extends the length of the hold unit frame, and ispivoted on each end thereof. Armature stop 36 is provided to limit thereturn travel of the armature 35 produced by return spring 54, afterde-energization of motor unit 34. Attached to the opposite side ofsupport member 32 is a series of stationary bars 37 having contacts 53thereon, and a row of movable contacts 38, the position of which arecontrolled by cards 39. There is provided a set of movable contacts 38on each card for each stationary bar 37, consequently, each card 39controls the opening and closing of six sets of electrical contacts. Thestationary bars 37 are spaced apart and supported on the support member32 by insulating blocks in a snap in arrangement designated 40, andconnections to the stationary bars 37 are brought out to the rear of thehold unit 14 by bus members 41 which extend through an insulating blockassembly 42 at the rear of the hold unit 14. In a similar manner,movable contacts 38 which are of the fiat spring type, extend throughinsulating block 42 at the rear of the hold unit 14 and connectionsthereto may be made at bus members 43. Bus members 41 and 43 can be morereadily identified by reference to FIGS. 3 and 5.

FIG. is an enlarged perspective view ofa select finger set 46 of thetype used in the present crossbar switch 13. Select finger set 46 iscomposed of two generally L-shaped fingers 27, joined at a bight portion47. As can be seen from HG. 10, each select finger 27 is deformed at apoint near bight 47 such that when the fingers 27 are free to move, theyare tensioned toward each other and in the absence of any restrainingforce actually cross each other. FIG. I! is a side view of the selectfinger set 46 as shown in FIG. I l, and at this point it should be notedthat the longer portion of the L of each finger is straight as opposedto prior art select fingers which had the corresponding L-portion bentat a predetermined angle. The significance of straight longer portion ofselect fingers 27 will become more apparent after a further descriptionof bold unit 14.

FIG. 8 is an enlarged perspective view of select finger holder 44 whichis used with the hold units 14 of the present crossbar switch 13. Selectfinger holder 44 is a one piece molded plastic unit, composed of acetalresin for example, which includes a plurality of mounting buttons 45,each having a groove 5! adapted to receive the bight portion 47 ofselect finger sets 46, and a plurality of mounting posts 48 having agenerally circular cross section.

Support member 32 of the hold unit 14 has a plurality of notches 49 inthe rear section of member 32, these notches being slightly greater thansemicircular and designed to receive the mounting posts 48 of the selectfinger holder 44. In FIG. 6, a portion ofone end ofselect finger holder44 ha been broken away to show the position of one of the notches 49,and FIG. 7 shows how the select finger holder 44 with the post 48 wouldjoin with the member 32. With this arrangement, the notches 49 beingslightly greater than semicircular and the post 48 being of circularnature, the select finger holder 44 can be easily snapped into place onthe rear portion of hold support member 32. This eliminates theheretofore known arrangement of individually mounting one holder foreach select finger set.

As can best be seen in FIGS. 5 and 6, when the select finger sets 46have been inserted into operative relationship with cards 39 and snappedinto place around the mounting buttons 45, a portion of the generallycircular bight 47 remains exposed. This portion can easily be grasped toremove a select finger 46 from the hold unit 44 should one of the selectfingers 27 become broken or bent. Thus it can be seen that removal of aselect finger set 46 is greatly simplified over that prior art whereinthe buttons were round and and the select fingers were not easilyaccessible once mounted on the button.

Each of the cards 39 has in its lower portion an aperture 50 which is ofthe generally boomerang shape, this feature being easily seen in FIG. 6.Select finger sets 46 are inserted in the hold unit 14 by firstseparating the fingers 27 so that they no longer cross, and insertingthe select fingers 27 through the apertures 50 of an associated pair ofcards. Next the bight portion 47 of the select finger set 46 is insertedinto the groove 51 of the corresponding mounting button 45, theresulting positioning of select finger set 46 being as shown in FIGS. 5and 6. For proper operation of the crossbar switch, it is necessary thatthe select fingers 27 normally be positioned in the apertures 50 of theindividual cards in the manner shown in FIG. 6 for those select fingersets 46 which have not been operated, i.e., in the right angle corner ofaperture 50. To meet this requirement, it is necessary that the selectfingers 27 be pretensioned such that each finger 27 in a particular settends to move toward the other, and that the free end of the selectfingers 27 tend to move away from the support member 32. The formerrequirement is accomplished by aforementioned bending the individualfingers at a point a short distance from bight 47 such that theynormally cross as shown in FIG. 10. The latter requirement hasheretofore been met by bending the individual select fingers at somepoint away from bight 47 so that after the finger sets have been mountedon the support member 32, they will normally be biased such that theirfree ends move away from the support member 32. As can best be seen fromFIG. 9, the mounting buttons 45 on select finger holder 44 have beendesigned such that after the select finger set 46 has been inserted intogroove 51 of button 45, an approximately 3 bias is placed on the selectfingers 27, resulting in moving the free ends of the select fingers 27away from the support member 32. This bias retains the select fingers 27in lower portion of aperture 50. Thus it can be seen that the originallyrequired pretensioning of the select fingers 27 is no longer necessarysince the downward bias on the lower portion of the apertures 50 is nowsupplied by the approximately 3 angle of groove 51 in mounting buttons45, Thus it can be seen that by using select finger holder 44 in holdunit 14, pretensioning of select fingers 27 in the second direction isno longer necessary, thus manufacturing of the select finger sets 46 issimplified greatly.

The crossbar switch 13 of the present invention operates in the samemanner as the crossbar switch disclosed in US. Pat. No. 3,445,795, andtherefore a detailed discussion of that operation is not necessary. Thepreliminary step in the operation of one of the cards 39 of the crossbarswitch 13 is shown in FIG. 6. One of the select bars 52 has beenrotated, as shown in FIG. 6, and operate finger 26 has positioned theassociated select finger 27 in the restricted area of aperture 50. Inthe next step, hold magnet assembly 33 is energized which in turnrotates armature 35 toward the core of electromagnet 34 which pushesselect fingers 27 toward support member 32. With the conditions as shownin FIG. 6, the only card 39 that would be moved by operation of armature35 would be the one in which the select finger 27 had been moved intothe restricted area of aperture 50. This card 39 would be moved, underthe control of the select finger 27 and armature 35, upward and themovable contacts 38 associated with the card 39 would mate with theassociated contacts 53 on stationary bars 37. As is conventional withthis type of crossbar switch, once the hold armature 35 has beenenergized and the preconditioned cards 39 moved so that their controlledmovable contacts 38 are mated with the stationary contacts 53, selectbars 52 are allowed to return to their normal position and the selectedcards 39 are retained in their new position under the control ofarmature 35 Although only one embodiment of the present invention hasbeen shown, it will be readily apparent to those skilled in the art thatthe teachings of the invention may be practiced in slightly variant formwhich will fall within the scope of the invention.

What is Claimed ls:

l. A cross-coordinate switching device comprising:

a frame;

a plurality of select units mounted on said frame, each of said unitsincluding electromagnetic select means and a select bar having aplurality of operate fingers selectively operated under the control ofsaid electromagnetic means;

a plurality of hold units mounted on said frame, each of said hold unitshaving a support, a plurality of movable contacts, a plurality ofstationary contacts, a plurality of actuating elements movably supportedin said hold unit, actuating element moving means, a plurality ofsubstantially U-shaped select finger pairs, each said pair having amounting end at the bight of the U and a free end opposite thereof, eachsaid select finger being operatively interposed between said movingmeans and a corresponding actuating element,

and said operate fingers being disposed in cooperative relationship withsaid select fingers for preconditioning predetermined ones of saidselect fingers to translate their corresponding actuating elements uponactuation of said moving means, thereby to move the respective movablecontacts into or out of engagement with the associated stationarycontacts;

and each said hold unit also including a unitary select finger holderhaving a plurality of mounting buttons each for receiving and supportingthe mounting end of the select fingers of a corresponding pair, andhaving mounting means adapted to frictionally engage said support suchthat said select finger holder, as a unit, may be readily snapped intoand out of place on said support.

2. The apparatus of claim 1 wherein said mounting buttons are generallysemicircular in shape and said mounting end of said pairs is ofgenerally circular shape, whereby when one of said pairs is mounted onthe respective button a portion of said mounting end remains exposed.

3. The apparatus of claim 2 wherein said buttons include a groove forpositioning said select fingers at an angle away from the plane of saidsupport.

4. The apparatus of claim 1 wherein said mounting means comprises aplurality of posts of generally semicircular shape and said supportincludes a corresponding plurality of notches adapted to receive saidposts and retain said select finger holder in place on said support.

5. The apparatus of claim 1 wherein said frame includes a channeledmember for providing additional strength to said frame.

6. The apparatus of claim 1 wherein said electromagnetic select meanscomprises a pair of electromagnets and an armature.

7. The apparatus of claim 6 wherein the plurality of pairs ofelectromagnets are located on one end of said frame and saidelectromagnets of each said pair are positioned on opposite sides of aframe member.

4: a a it

1. A cross-coordinate switching device comprising: a frame; a pluralityof select units mounted on said frame, each of said units includingelectromagnetic select means and a select bar having a plurality ofoperate fingers selectively operated under the control of saidelectromagnetic means; a plurality of hold units mounted on said frame,each of said hold units having a support, a plurality of movablecontacts, a plurality of stationary contacts, a plurality of actuatingelements movably supported in said hold unit, actuating element movingmeans, a plurality of substantially U-shaped select finger pairs, eachsaid pair having a mounting end at the bight of the U and a free endopposite thereof, each said select finger being operatively interposedbetween said moving means and a corresponding actuating element, andsaid operate fingers being disposed in cooperative relationship withsaid select fingers for preconditioning predetermined ones of saidselect fingers to translate their corresponding actuating elements uponactuation of said moving means, thereby to move the respective movablecontacts into or out of engagement with the associated stationarycontacts; and each said hold unit also including a unitary select fingerholder having a plurality of mounting buttons each for receiving andsupporting the mounting end of the select fingers of a correspondingpair, and having mounting means adapted to frictionally engage saidsupport such that said select finger holder, as a unit, may be readilysnapped into and out of place on said support.
 2. The apparatus of claim1 wherein said mounting buttons are generally semicircular in shape andsaid mounting end of said pairs is of generally circular shape, wherebywhen one of said pairs is mounted on the respective button a portion ofsaid mounting end remains exposed.
 3. The apparatus of claim 2 whereinsaid buttons include a groove for positioning said select fingers at anangle away from the plane of said support.
 4. The apparatus of claim 1wherein said mounting means comprises a plurality of posts of generallysemicircular shape and said support includes a corresponding pluralityof notches adapted to receive said posts and retain said select fingerholder in place on said support.
 5. The apparatus of claim 1 whereinsaid frame includes a channeled member for providing additional strengthto said frame.
 6. The apparatus of claim 1 wherein said electromagneticselect means comprises a pair of electromagnets and an armature.
 7. Theapparatus of claim 6 wherein the plurality of pairs of electromagnetsare located on one end of said frame and said electromagnets of eachsaid pair are positioned on opposite sides of a frame member.